This disclosure relates to a gas turbine engine, and more particularly to a blade outer air seal that may be incorporated into a gas turbine engine.
Gas turbine engines typically include a compressor section, a combustor section and a turbine section. During operation, air is pressurized in the compressor section and is mixed with fuel and burned in the combustor section to generate hot combustion gases. The hot combustion gases are communicated through the turbine section, which extracts energy from the hot combustion gases to power the compressor section and other gas turbine engine loads.
Both the compressor and turbine sections may include alternating series of rotating blades and stationary vanes that extend into the core flow path of the gas turbine engine. For example, in the turbine section, turbine blades rotate and extract energy from the hot combustion gases that are communicated along the core flow path of the gas turbine engine. The turbine vanes, which generally do not rotate, guide the airflow and prepare it for the next set of blades.
A casing, associated with either the compressor section or the turbine section, may include blade outer air seals that provide an outer radial flow path boundary of the core flow path. The blade outer air seals may be positioned in relative close proximity to a blade tip of each rotating blade in order to seal between the blades and the casing.
The rotating blades and case generally have designed clearances. If the designed clearances are not maintained, a negative effect on gas turbine engine performance may result. The case typically includes an outer air seal located in the case opposite the rotor blade tip to aid in maintaining the clearances within a selected range. The outer air seals are mounted in the case, but often high heat transfer results from the gas path up into the flanges of the case. This results in faster case thermal expansion response than is often desirable, resulting in clearances outside of the selected range. Mass is often added to the case to slow the case response but has limited effectiveness and also increases the weight of the gas turbine engine.